diff --git a/lamps/LampGroup.py b/lamps/LampGroup.py
index b6f72ef..b6244bd 100644
--- a/lamps/LampGroup.py
+++ b/lamps/LampGroup.py
@@ -20,7 +20,7 @@ class LampGroup:
     def activateNext(self):
         self.lamps[self.currentLamp].activate()
 
-        if self.currentLamp == len(self.lamps):
+        if self.currentLamp == len(self.lamps) - 1:
             return
 
         self.currentLamp += 1